Chemical Wastes in our Atmosphere—An Ecological Crisis

Abstract

A large variety of chemical wastes is added to our atmosphere from nu merous human activites. Some of these, such as sulfur and nitrogen oxides (which produce acid rain), ozone, metals, and hydrocarbons, have reached high concentrations in industrialized and urbanized regions of the globe and are causing an ecological crisis. Acid rain and snow have been falling on increasingly widespread areas of the world during the past several decades. Large areas of North America, Europe, and Asia now receive rain that is, on average, 10 to greater than 30 times more acidic than would be expected for unpolluted atmospheres. Fre quently, individual rainstorms or cloudwater events have pH values of less than 3. Dry deposition of acidic substances (gases and particles) to natural ecosystems may equal inputs from rain and snow. Effects of air pollution on surface waters, forests, and crops are very difficult to quantify because these natural systems are exceedingly variable and complex. Nevertheless, thousands of lakes and streams in North America and Europe have become so acidic that they cannot support viable populations of fish and other organisms. Highly acidic precipitation events coupled with high atmospheric concentrations of ozone and metals can cause plant damage. Crop loss from ozone damage in the United States is estimated at 6 to 7% annually. The environmental and economic conse quences of air pollution have yet to be evaluated fully, but atmospheric ozone and inputs of acids and metals to terrestrial and aquatic ecosystems clearly represent a potential ecological crisis. Various historical and transboundary aspects of these air pollution problems have become controversial political and economic issues, particu larly between states within the United States, between the United States and Canada, and between various countries in Europe. The solution to this many-faceted environmental problem represents an enormous scientific and political challenge.